To me, it's almost entirely outclassed. Really, Simipour's main niche is its speed. Pretty much anything Simipour can do (well), Samurott can do better. It has better bulk and a noticable difference in base SpA. Simipour can run a physical set, but this would usually carry Acrobatics, and without STAB to back it up, he's going to miss that item slot used for a Flight Gem once it has been consumed. Probably the most viable set that Simipour can run better than Samurott is a mixed set to help get by the sturdiest special walls in NU such as Lickilicky and Regice.
Ultimately, if you can manage to run an effective set on Simipour, that's great. But in my opinion, there is usually someone who is going to fill that role better.